The rheology of fluid gels containing low acyl gellan gum is notoriously dependent on the processing conditions under which the fluid gel is formed. The efficacy of the processing conditions typically has a profound impact on the bulk properties of the final gelled system.
The critical stage in the processing of gellan gum occurs when gellan polymer strands crosslink to form an extended molecular network. Crosslinking can be determined by simple inspection of the structure of low acyl gellan gum. The repeating tetrasaccharide backbone contains a glucuronic acid residue, and the carboxyl group on this residue can share cations with adjacent gellan strands, leading to weak coordinate bonds bridging multiple strands, causing crosslinking which provides the extended molecular network.
Furthermore, crosslinking can be controlled by adjusting the temperature of the solution: above a certain temperature, sometimes referred to as the gelation temperature, crosslinking will not occur.
One typical known processing scheme of gellan gum includes the following steps: heat a solution of gellan gum to an elevated temperature above the gelation temperature to avoid crosslinking; then add crosslinking cations and allow complete dissolution of gellan gum and the cations, the elevated temperature being sufficiently high to ensure such complete dissolution; and then cool the solution below the gelation temperature to cause crosslinking This known process allows all crosslinking cations to distribute uniformly throughout the solution before gelation, and allows the exact moment of gelation to be controlled.
However, this approach is not desirable because of the energy required during the heating and cooling cycle.
Those skilled in the art of producing such gels know that rapid or immediate crosslinking is undesirable, because such rapid crosslinking prevents uniform distribution of the cations. This in turn leads to a system with heterogeneous rheology due to localized highly-crosslinked domains, and gel domains with low crosslinking.
There is accordingly a need in the art for a method of manufacturing a gel comprising gellan gum which has lower energy consumption than known manufacturing methods and can consistently provide homogeneous rheological properties in the gel.
There is also a need in the art for a method of manufacturing a gel comprising gellan gum which has a reduced processing time and energy consumption as compared to known manufacturing methods.